In oracle, generally speaking, there are number of facts that I will mention in following section:
Therefore, your question, "to see all tablespaces and datafiles belong to SCOTT" is s bit wrong.
However, there are some DBA views encompass information about all database objects, regardless of the owner. Only users with DBA privileges can access these views: DBA_DATA_FILES, DBA_TABLESPACES, DBA_FREE_SPACE, DBA_SEGMENTS.
So, connect to your DB as sysdba and run query through these helpful views. For example this query can help you to find all tablespaces and their data files that objects of your user are located:
SELECT DISTINCT sgm.TABLESPACE_NAME , dtf.FILE_NAME
FROM DBA_SEGMENTS sgm
JOIN DBA_DATA_FILES dtf ON (sgm.TABLESPACE_NAME = dtf.TABLESPACE_NAME)
WHERE sgm.OWNER = 'SCOTT'